P2.3 Work, energy and momentum

Question 1

What is ‘work done’?

Answer 1

Work is done on an object when a force makes the object move

Question 2

Work done is equal to …?

Answer 2

…the energy it transfers

Question 3

What is the equation for work done?

Answer 3

Work done(J) = force(N) x distance (moved in the direction of the force)(m)

Question 4

How is work done to overcome friction transferred?

Answer 4

as thermal energy that heats the objects that rub together and he surrounding

Question 5

What is power and the the equation for it?

Answer 5

Power is the amount of work done/energy transferred in a given time
Power = work done/time

Question 6

What objects contain GPE?

Answer 6

any object that is raised above the ground

Question 7

What is the equation for GPE?

Answer 7

GPE=mass x gravitational field strength x height

Question 8

What happend when an object goes up; and then down?

Answer 8

Up-GPE increases

Down-GPE decreases

Question 9

What is the equation for Kinetic energy?

Answer 9

KE=1/2 x mass x velocity^2

Question 10

What is the unit for energy?

Answer 10

Joules (J)

Question 11

What is Elastic potential energy

Answer 11

Elastic potential energy is stored in an elastic object when work is done on that object

Question 12

What is the equation for momentum?

Answer 12

Momentum(kg/ms) = mass(kg) x velocity(m/s)

Question 13

Explain the conservation of momentum

Answer 13

In a closed system, the total momentum before and after an event is the same

Question 14

Han impact force be reduced?

Answer 14

Increasing/making the impact time longer

Question 15

What happens when two vehicles collide?

Answer 15

they exert equal and opposite forces on each other

their total momentum is unchanged

Question 16

How can car safety be increased?

Answer 16

seat belts, crumble zones, air bags, side impact bars

Question 17

What do side impact bars and crumple zones do?

Answer 17

‘give ‘way’ in an impact, increasing the impact time

Question 18

How do seat belts improve car safety? (momentum)

Answer 18

seat belts increase the time taken for change in momentum/impact therefore reducing the force on the body:impact time increases, time decreases
they also spread the force across the chest/body (like air bags)